[PATCH v4 0/6] sparc32: replace sp_banks with memblock

[Magnus Lindholm <linmag7@gmail.com>]

Replace the sparc32-private sp_banks memory description with memblock.

The first two patches convert the SRMMU consumers that already run after
bootmem_init() has populated memblock. The third patch moves memblock
population to prom_meminit() and applies the mem= limit there. Patch 4
removes an unused address bitmap before patch 5 moves the early memory
setup into setup_32.c. Patch 6 removes the now-unused sp_banks array.

This work is based on an earlier eight-patch series by Sam Ravnborg.
Patch 2 directly carries over Sam's memblock sizing conversion. The series
has otherwise been substantially reorganized and reworked for the current
kernel. It retains the sparc32 mem= command-line option by using
memblock_enforce_memory_limit() and uses memblock's exclusive range-end
semantics throughout.

The series applies on top of the sparc32 phys_base and Viking fixes,
rebased onto Linux 7.3-rc1. The prerequisite tip is recorded below as the
base commit. setup_memory() preserves relocated-kernel handling by
removing RAM below the physical address to which PAGE_OFFSET maps.

Link: https://lore.kernel.org/sparclinux/20260816075141.3489194-1-linmag7@gmail.com/T/#t

The v1 series was boot tested on a Sun SPARCstation 20 with dual
SuperSPARC-II CPUs (SM71).
The v2 series was boot tested on a Sun SPARCstation 20 with dual
ROSS HyperSPARC (RT626) CPUs.
The v3 series was cross-compiled with the SPARCstation 20 and LEON
configurations as well as boot tested on a Sun SPARCstation 20
with dual ROSS HyperSPARC (RT626) CPUs.

The v4 series was cross-compiled with the SPARCstation 20 SMP configuration
and a sparc32_defconfig-derived LEON configuration, both with HIGHMEM
enabled. Boot tested on a SPARCstation 20 SMP (ROSS)

Changes in v4:
- Use max_pfn in LEON's _pfn_valid() check, preserving the bounds of
  last_valid_pfn instead of restricting the check to lowmem, as requested
  by Andreas Larsson.
- Correct the description: LEON systems can use highmem.
- Carry Sam's Reviewed-by tag on patch 5; all six patches now retain his
  review tags.
- Rebase onto Linux 7.3-rc1 plus the three prerequisite patches; adjust
  patch 6's context without changing its code changes.

Changes in v3:
- Add Sam's Reviewed-by tag to patch 4.
- Initialize max_pfn in patch 5 and use it as the highmem zone limit.
- Use PHYS_PFN() instead of open-coded PAGE_SHIFT conversions in patch 5.
- Remove the obsolete highstart_pfn and highend_pfn declarations.
- Use the generic PFN limit declarations from linux/memblock.h.
- Document removal of the duplicate private HIGHMEM summary.

Changes in v2:
- Add Sam's Reviewed-by tags to patches 1-3 and 6. Patch 6 is the
  unchanged source change from patch 5 in v1, renumbered by the new patch.
- Drop the unused sparc_valid_addr_bitmap in a preparation patch.
- Use for_each_mem_pfn_range() and the standard max_low_pfn variable in
  the early memory setup. The change to LEON's PFN check made in v2 is
  corrected in v4 to preserve its original bounds.

Suggested-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://lore.kernel.org/r/20260817153237.GA702187@ravnborg.org
Link: https://lore.kernel.org/r/20260901214611.60560-1-linmag7@gmail.com

Magnus Lindholm (6):
  sparc32: use memblock when mapping the kernel
  sparc32: use memblock to find available system memory
  sparc32: populate memblock from the PROM memory map
  sparc32: drop unused valid address bitmap
  sparc32: move early memory setup to setup_arch
  sparc32: drop sp_banks

 arch/sparc/include/asm/highmem.h    |   3 -
 arch/sparc/include/asm/leon.h       |   2 +-
 arch/sparc/include/asm/page_32.h    |  16 ---
 arch/sparc/include/asm/pgtable_32.h |   3 +-
 arch/sparc/include/asm/pgtsrmmu.h   |   1 -
 arch/sparc/kernel/setup_32.c        | 112 ++++++++++---------
 arch/sparc/mm/init_32.c             | 167 +---------------------------
 arch/sparc/mm/leon_mm.c             |   1 +
 arch/sparc/mm/srmmu.c               |  69 ++++--------
 arch/sparc/prom/memory.c            |  51 ++-------
 10 files changed, 98 insertions(+), 327 deletions(-)


base-commit: ff3cbaedcebcb60f8f13fa4dd667116f29cd53e4
-- 
2.43.0